A professor grades 120 research papers and reports that the average score was 80%.What do we know about the sum of the differences of these 120 scores from their mean of 80%?
A) The sum of the differences is minimal.
B) The sum of the differences is 80%, the same as the mean.
C) The sum of the differences is equal to zero.
D) It is impossible to know without knowing each of the 120 scores.

Question

Quizplus · Accepted Answer

The sum of the differences from the mean is always equal to zero, regardless of the number of scores being averaged. This is because for every score that is above the mean, there is a corresponding score that is below the mean, causing the positive and negative differences to cancel each other out when added together. Therefore, we know that the sum of differences in this case is equal to zero.

A Professor Grades 120 Research Papers and Reports That the Average